So I got the alignment done today. The van doesn't really drive any differently, but he made a couple of small adjustments, and just confirmed that everything is tight and good to go.
The mechanic did point out that one of the rear tires has been patched on the sidewall. This must have been done by the previous owner, because all my patches have been tread. Sidewall patching is a big no-no. And to top things off, the rear tires are the ones that will be heavily loaded for our big trip. They HAVE been fine on all our previous trips...but still...it makes me nervous.
So anyway, I'm going to ask around for pricing to replace the two rear tires at this time. If I get something decent back, I may bite. Replacing two tires isn't really in my budget right now, as it is going to eat into our trip budget, but it doesn't hurt to get pricing, and if its good, maybe I'll bite. I dunno. The four tires are due to be replaced in the spring anyways. I just don't really want to pay for them NOW.